Post-mortems are due to be carried out to try to establish a cause of death for Mr Chapman of Bifield, Orton Goldhay, Peterborough, and Mr Slaboszewski, who is also from the city.

Police have linked the killings with the murder of Kevin Lee whose body was found in a roadside ditch at nearby Newborough on March 30. The 48-year-old, of Fletton, Peterborough, had been stabbed to death.

Mr Lee was last seen at 2pm on Good Friday and reported missing at 10.40pm that day, just after his metallic, light blue Mondeo was discovered burnt-out near a farm in Yaxley.

A woman and four men have so far been arrested in connection with his murder in what police have described as a complex investigation, dubbed Operation Darcy.

A 36-year-old man has been charged with perverting the course of justice and has been remanded to appear at Peterborough Crown Court, later this month. Two men, 23 and 32, arrested over the weekend have been released on bail.

A 47-year-old man arrested 140 miles away in Hereford earlier this week remains in custody while a 30-year-old woman, also arrested in the city, has been detained under the Mental Health Act. She is being assessed in a secure unit.

Both were detained by West Mercia Police, which has said it is liaising closely with colleagues in Cambridgeshire.